Wave measurements

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This page, under construction, is dedicated to the wave measurements - and most especially to the directional wave spectra measurements - on moored buoys. Contributors are welcomed.


Background

In 2000, W. Jones and S. Keogh (Met Office) showed that K-pattern buoys are capable of being used to produce directional wave spectra. For their study [Ref. 1], a K-pattern buoy was equipped with a Triaxys wave sensor and moored close to a directional waverider from Datawell.


Motion sensors for directional wave measurements

1. Hippy (Datawell, Netherlands)
There are 4 different versions of the Hippy motion sensor: Hippy 40, 120A, 120B and 120C. All of these versions have the following properties in common:

  • measures pitch, roll, vertical acceleration and heave
  • reference is a gravity stabilized platform
  • high pass filter for heave output
  • flexible supply voltage: 10 to 30 VDC

Hippy 40 equips Datawell directional waveriders Mark II (and III?). It also equips the French K-pattern moored buoys to provide omni-directional wave spectra.


2. MRU (Kongsberg, Norway)
The MRU (Motion Reference Unit) is specifically designed to measure roll, pitch, yaw and heave motion in marine applications. It utilizes military-grade accelerometers and several models of quality gyros, depending on the application, to meet customers' accuracy and cost requirements.

MRUs are used by Oceanor (Norway) for WaveScan and SeaWatch moored buoys. One sensor of that kind is also used by CETMEF (France) for the 12m-discus aid-to-navigation Ushant buoy.


3. Triaxys (Axys Technologies, Canada)
Two Triaxys products can be used to measure wave directions on data buoys :

  • The Triaxys Directional Wave Sensor is comprised of three accelerometers and three rate sensors that ultimately measure the total displacement along the three orthogonal axes of the floating platform, x, y, z or HNE. In addition, this sensor is equipped with a gimbaled fluxgate compass to measure true magnetic direction.
  • The Triaxys Motion Sensor also contains three accelerometers and three angular rate sensors and outputs the raw motion of the platform.


Directional wave buoys

1. Datawell

  • Directional waveriders Mark II and III
  • GPS wave buoys


2. Oceanor

  • SeaWatch and WaveScan buoys
  • Smart-820 buoy


3. Triaxys


4. NDBC


5. CETMEF


References

[1] Jones W. and S. Keogh (2000). Some preliminary results from a Met Office Open Ocean Buoy fitted with a Triaxys wave sensor. Presented at the DBCP Workshop, Victoria, Canada, October 2000. DBCP Technical Document No. 19, pp 85-107.


Useful links


Contributors to the present page

If you think your name must appear as contributor for the present page, don't hesitate to add it here below.
--Blouch 09:52, 14 Feb 2005 (CET)